Try making these: http://www.today.com/food/recipes-get-your-kids-gobble-good-you-greens-t24066 (replace kale with spinach and you will get spinach chips) http://www.foodnetwork.com/recipes/ina-garten/parmesan-roasted-broccoli-recipe.html and cauliflower rice: http://www.thekitchn.com/how-to-make-cauliflower-rice-couscous-cooking-lessons-from-the-kitchn-203344 These are easy to make, healthy and delicious even to the kids. They may not know they are eating their veggies. ;)
You can try to involve him in growing up own leafy vegetables so he will be feeling more appreciate and willing to take in own grown vegetables. Another way is to use food face kids dinner plate to encourage him to decorate the face using vegetables and eat them. You can get from amazon for about USD12.90. Here is a vege patties recipe which is very easy to prepare and tasty: http://littlegrazers.com/mini-vegetable-and-cheddar-patties/
Present the vegetables and fruits in a creative manner. Kids respond to colours and interesting shapes and this might even distract them from acknowledging the veggies as things they do not like. As an adult, even I find it hard to eat foods if they don't look too attractive haha. This website might inspire you : http://t.meredith.ly/MIDZVuf
thanks